Project Title: Effect of Alcohol Use on Waterpipe Smoking Patterns and Toxicant Exposure Project Summary/ Abstract: Waterpipe (WP) smoking in the US is on the rise and beginning to overtake cigarettes as the most popular method of tobacco use among young adults. Unfortunately, WP smoking is associated with many of the same negative health outcomes as cigarettes such as cancer, lung disease, respiratory illness, and cardiovascular disease. The co-occurrence of alcohol use and WP smoking is quite common among young adults. Relative to those who do not use WP, WP smokers are estimated to be more than twice as likely to use alcohol and frequently consume alcohol immediately before or during a WP smoking session. Of concern, the cigarette smoking literature suggests that smokers smoke more cigarettes when they drink alcohol and have a more difficult time abstaining from smoking, resulting in more exposure to nicotine and tobacco-related toxicants. These findings cannot be directly applied to WP smoking due to unique aspects of WP smoking (e.g., smoking patterns, smoke may be easier to inhale, WP is typically smoked in groups). To date, no study has experimentally and systematically investigated the impact of alcohol on WP smoking behaviors, resultant exposure to tobacco-related toxicants, or abuse liability. The proposed study will provide this needed scientific evidence. Using a randomized crossover-design, 40 current WP smokers will complete two counterbalanced WP smoking sessions (alcohol vs. placebo) that are preceded by 24 hours of alcohol abstinence and 12-hour tobacco abstinence. Sessions will be separated by a standard 48-hour washout period, and WP tobacco nicotine levels will be held constant across sessions. Measures of smoking behavior (puff topography) and acute toxicant exposure (CO boost and plasma nicotine) will be collected, in addition to self-report measures of abuse liability, intentions for continued use, and importance of concurrent alcohol consumption for using WP. If alcohol consumption were determined to influence users to initially try WP, increase their willingness to continue to use the product, and/or make it more palatable to puff more frequently or take longer/deeper puffs, then concurrent alcohol use would be contributing to the initiation and maintenance of WP dependence. This innovative study, in its systematic examination of the impact of co-use of alcohol and WP, will provide the scientific foundation needed to establish effective regulatory strategies for the distribution and sales of WP tobacco and alcohol. In addition, this project will serve as an incredibly valuable training experience by providing an opportunity to learn new assessments of WP smoking and drug-drug interactions while learning from leading experts in the field of WP smoking and gaining an appreciation for interdisciplinary collaboration.